how to keep a cat away from a "peeing area"

I have two cats that both had UTIs. The vets confirm that they are both better, but the inappropriate peeing continues. One cat had repeatedly used the corner at the bottom of the stairs. This past weekend, we began remodeling the kitchen and when we ripped up the rug and floorboards in that area, the odor was AWFUL. We poured 2 gallons of Nature's Miracle and PetZyme into the area and it did NOTHING. The smell is there, strong as ever, and we've determined that, short of disassembling the entire house, there is no way to get rid of that odor.

I know the cat hasnt been returning to the area, since they have all been locked in the basement since the remodeling began (so that they dont walk in tile cement, etc).

So, the smell is still there, and I know that as soon we're done remodeling and we let the cats back upstairs, she is going to pee there again, since the odor is there and its REALLY strong. I guess the only thing to do is prevent her from returning there and peeing again. Any suggestions for how to do this?

Similarly, the other cat who had a UTI chose the leather couch as his preferred peeing spot. the UTI is gone but he still loves to pee there. the couch REEKS and the enzyme cleansers dont really help, because there is so much pee in there and they cant reach it all. Can we just teach him not to go near the couch?

We've tried tinfoil and they just pee on the tinfoil.

If the floor boards are still exposed try cleaning it with vodka or a mixture of hydrogen peroxide (1 cup), Baking soda (1 teaspoon) and disk soal (1 drop). I'd try the peroxide mixture first. I should foam up when you pour it on but apply it liberally and allow to air dry before re-applying. If that doesn't work (you can still smell it up close) then try soaking the area in vodka and allow that to air dry. As for the couch, I'm afraid if you can't get rid of the smell you may have to get rid of the couch to stop the behavior and I don't have any ideas for cleaning leather. You could try the same peroxide mixture but it won't work if you can't get to all of the urine stains. The only other idea I have is to put a citrus air freshner under, next to or very near the couch where the cat is peeing. The citrus smell should act as a detterant and it's worked on my Frankie.

I had a pee smell in the hardwood floors under my litter box at my last house. I actually had to repeat the Nature's Miracle treatment on that spot about a dozen times before the smell was finally gone. I actually got done on the floor and smelled over the entire area and actually got it isolated to the crack between the floor boards. I'd saturate it, scrub it in with a brush and just let it completely dry. Then repeated over and over again. We were selling the house and we had to get the smell out.

I just wanted to note that I gave the wrong recipe for the odor remover... (I've fixed it in post) but it should be 1 TEAspoon os baking soda NOT 1 tablespoon. Sorry!

I don't know if these floorboards are your actual floor or your subfloor (I'm sorry if you said it.. the brain is on vacation today... ) but if it's an area you don't mind painting, you can try a layer of kilz or zinsser primer (or some other odorblocking primer) and then a layer of polyurethane over it. That usually blocks the smell from seeping out of the wood.